xlC on AIX needs an explicit cast for the alignment to prevent:
"/net/usr.work/openjdk/nb/rs6000_64/nightly/jdk10-hs/hotspot/src/cpu/ppc/vm/c1_Runtime1_ppc.cpp", line 254.25: 1540-0218 (S) The call does not match any parameter list for "align_up".
"/net/usr.work/openjdk/nb/rs6000_64/nightly/jdk10-hs/hotspot/src/share/vm/utilities/globalDefinitions.hpp", line 532.10: 1540-1283 (I) "template <class T, class A> align_up(T, A)" is not a viable candidate.

In addition, type cast in vm_version_ppc is needed for both linux and AIX:
/net/usr.work/openjdk/nb/linuxppc64/nightly/jdk10-hs/hotspot/src/cpu/ppc/vm/vm_version_ppc.cpp:700:40: error: invalid conversion from 'char*' to 'address {aka unsigned char*}' [-fpermissive]